1. Field of the Invention
The present invention relates to hammer drills, and more particularly, to an impact mechanism for a hammer drill.
2. Background of the Invention
When drilling through hard surfaces such as rocks or stone, many times it is desirable to impart a reciprocating motion to the drill bit to facilitate drilling. This hammering motion of the drill bit helps break up the material while the rotating of the drill bit allows the broken up material to be removed from the hole being drilled.
A primary disadvantage associated with existing impact mechanisms for hammer drills is the fact that in order to accomplish a desired high blows per minute (BPM) for efficient hammer drill performance, an undesirable high output speed is required. High BPM can also be achieved by increasing the number of ramps on the impact mechanism. However, an increased number of impact ramps tend to produce a “skipping” effect and efficiency loss due to the smaller area of surface contact for each ramp.